diff options
| -rw-r--r-- | include/net/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 67 |
2 files changed, 18 insertions, 50 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index f9777dbede75..c5868471abae 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -591,7 +591,6 @@ extern void tcp_initialize_rcv_mss(struct sock *sk); extern int tcp_mtu_to_mss(struct sock *sk, int pmtu); extern int tcp_mss_to_mtu(struct sock *sk, int mss); extern void tcp_mtup_init(struct sock *sk); -extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt); extern void tcp_init_buffer_space(struct sock *sk); static inline void tcp_bound_rto(const struct sock *sk) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index b531710596ec..c7398f05d12b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2792,65 +2792,36 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked, tcp_xmit_retransmit_queue(sk); } -void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt) +static inline void tcp_ack_update_rtt(struct sock *sk, const int flag, + s32 seq_rtt) { - tcp_rtt_estimator(sk, seq_rtt); - tcp_set_rto(sk); - inet_csk(sk)->icsk_backoff = 0; -} -EXPORT_SYMBOL(tcp_valid_rtt_meas); + const struct tcp_sock *tp = tcp_sk(sk); + + /* Prefer RTT measured from ACK's timing to TS-ECR. This is because + * broken middle-boxes or peers may corrupt TS-ECR fields. But + * Karn's algorithm forbids taking RTT if some retransmitted data + * is acked (RFC6298). + */ + if (flag & FLAG_RETRANS_DATA_ACKED) + seq_rtt = -1; -/* Read draft-ietf-tcplw-high-performance before mucking - * with this code. (Supersedes RFC1323) - */ -static void tcp_ack_saw_tstamp(struct sock *sk, int flag) -{ /* RTTM Rule: A TSecr value received in a segment is used to * update the averaged RTT measurement only if the segment * acknowledges some new data, i.e., only if it advances the * left edge of the send window. - * * See draft-ietf-tcplw-high-performance-00, section 3.3. - * 1998/04/10 Andrey V. Savochkin <saw@msu.ru> - * - * Changed: reset backoff as soon as we see the first valid sample. - * If we do not, we get strongly overestimated rto. With timestamps - * samples are accepted even from very old segments: f.e., when rtt=1 - * increases to 8, we retransmit 5 times and after 8 seconds delayed - * answer arrives rto becomes 120 seconds! If at least one of segments - * in window is lost... Voila. --ANK (010210) */ - struct tcp_sock *tp = tcp_sk(sk); + if (seq_rtt < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) + seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr; - tcp_valid_rtt_meas(sk, tcp_time_stamp - tp->rx_opt.rcv_tsecr); -} - -static void tcp_ack_no_tstamp(struct sock *sk, u32 seq_rtt, int flag) -{ - /* We don't have a timestamp. Can only use - * packets that are not retransmitted to determine - * rtt estimates. Also, we must not reset the - * backoff for rto until we get a non-retransmitted - * packet. This allows us to deal with a situation - * where the network delay has increased suddenly. - * I.e. Karn's algorithm. (SIGCOMM '87, p5.) - */ - - if (flag & FLAG_RETRANS_DATA_ACKED) + if (seq_rtt < 0) return; - tcp_valid_rtt_meas(sk, seq_rtt); -} + tcp_rtt_estimator(sk, seq_rtt); + tcp_set_rto(sk); -static inline void tcp_ack_update_rtt(struct sock *sk, const int flag, - const s32 seq_rtt) -{ - const struct tcp_sock *tp = tcp_sk(sk); - /* Note that peer MAY send zero echo. In this case it is ignored. (rfc1323) */ - if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) - tcp_ack_saw_tstamp(sk, flag); - else if (seq_rtt >= 0) - tcp_ack_no_tstamp(sk, seq_rtt, flag); + /* RFC6298: only reset backoff on valid RTT measurement. */ + inet_csk(sk)->icsk_backoff = 0; } /* Compute time elapsed between (last) SYNACK and the ACK completing 3WHS. */ @@ -2989,8 +2960,6 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, if (sacked & TCPCB_SACKED_RETRANS) tp->retrans_out -= acked_pcount; flag |= FLAG_RETRANS_DATA_ACKED; - ca_seq_rtt = -1; - seq_rtt = -1; } else { ca_seq_rtt = now - scb->when; last_ackt = skb->tstamp; |